FAQs:
Why don't I connect at 33.6 or 56k?

The very first thing you should consider is whether or not you've installed the most current drivers for your perticular modem. Next, remember that reported initial connect speeds won't necessarily be dependable or even comparable from modem to modem or location to location. The reason is that V.34 modems can (and often do) speed shift up and down after the initial connection, and do so in a manner that is dependent on the particular connection as well as the particular equipment (including firmware versions) at each end. Some modems connect at a more conservative speed and then quickly upshift as conditions allow; other modems connect at a more aggressive speed only to quickly downshift (or worse, lose performance due to excessive errors). Analog X provides a free product called "NetStat Live" that can tell you the actual rate of data being transferred.

Proof of the this-much-bandwidth-equals-this-baudrate argument has been provided on the US Robotics WWW site. You will also find much interesting information about dropped connections and other annoyances of the Internet.

Ameritech considers your phone line to be within acceptable operating parameters if (among other electrical statistics) you can talk on the line with a "bandwidth" of 300 to 3000 Hz. (That is, the phone is working properly if sounds in that range come through.) This is not just an Ameritech spec, it's pretty standard throughout North America.

If you have 300 to 3000hz bandwidth, and no electrical or other problems with the line, you have enough bandwidth for a 21600 BPS connection with your v.34 modem. Connect rates higher than this mean that your telephone company is providing you connection quality "above-and-beyond" their responsibility for phone service. The phone company has no contractual obligation to supply digital throughput of higher bandwidth on regular voice lines.

Customers seeking to increase their line quality must first understand that any requests to get the Telephone Company to improve POTS service beyond normal specs may be met with an outright "No." The phone company provides GUARANTEED data throughput for consumers, and they call it ISDN. If the phone company is willing to help, some things that can help are removing "bridge taps" and capacitors installed in the circuit to improve voice quality. The test for loss at various bandwidth levels (the critical one for modems, that detects un-obvious flaws) is called a "slope test", and is done with high-end expensive test equipment.

If you consistently connect at lower speeds (e.g., 24000 or even 21600), there may still not be much that you can do, but you can at least try the following:

  • If you have your modem connected to the phone line through a surge suppresser, try it without the surge suppresser. Many surge suppressers can interfere with modem communications.


  • If possible, test for premises problems by disconnecting all your premises wiring (and equipment) from the incoming telco terminating block, and hooking your modem directly to it. If your connections are better, you have a premises problem that you may be able to isolate and fix. Premises problems (faulty wiring and/or equipment like cheap phones and fax machines) are a frequent cause of 28800 connection problems.


  • If that doesn't help, listen carefully to the quality of your voice connections. Note that you must dial a known quiet number, since many otherwise good phone lines exhibit excessive noise until you actually connect. (Dialing a single digit is not enough.) After you connect, if you hear more than very faint hiss and/or hum, then you probably have a line problem.


  • While a quiet line is important, there are other line problems that can reduce your speed: bandwidth (frequency response), distortion, etc. It is difficult to test for these problems without proper test equipment, but it's still a good idea to listen carefully for audible problems, particularly if you can find a number that will send you test tones.


  • You may be able to get your phone company to improve the quality of your line. Since phone companies are often reluctant or even unwilling to work on data problems, it may help to report that you are also having fax problems. Or you can try asking for a data or fax "specialist." Ideally you want the service technician to bring the right kind of test equipment, a sophisticated line or transmission test set, not just the normal basic tester. It may also help to ask for a BERT (bit error rate tester) or "data test set."


  • Sometimes switching to a different cable pair from the CO (central office) will help. In extreme cases the author has resorted to ordering a new line, making sure that it is good when installed, and then canceling the old line.


  • You may be told that you need a special "data" line, more properly called a "conditioned" circuit, which is considerably more expensive than a standard "voice-grade" circuit. Don't waste your money. All you need is a good quality "voice-grade" circuit.


  • A final note: Add-on noise filters will not help -- they are the modem equivalent of snake oil. Your 28800 modem already has all the filtering it can use. An add-on filter will do nothing at best, and it may well make things worse.



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